Figure 3.

Timing and sequence of positive tests among healthcare workers with coronavirus disease 2019 (COVID-19). Each row represents all test results for each prevalent and incident case over the study period. Gray shading indicates each participant’s follow-up time. Dots represent reverse-transcription polymerase chain reaction (RT-PCR) results and boxes represent serological results. Blue coloring represents negative RT-PCR or serological results; red coloring, positive RT-PCR or confirmed positive serological results. Orange boxes represent unconfirmed positive serological results. The thickness of the red boxes is correlated with the number of confirmed positive serological results (eg, 2 or 3 positive antibody test results).